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71.
This article has two purposes. Firstly, a validation exercise of the modal summation technique for the computation of synthetic strong-motion records is performed for two regions of Europe (Umbria-Marche and south Iceland), using a variety of region specific crustal structure models, by comparing the predicted ground motion amplitudes with observed motions. It is found that the rate of decay of ground motions is well predicted by the theoretical decay curves but that the absolute size of the ground motions is underpredicted by the synthetic time-histories. This is thought to be due to the presence of low-velocity surface layers that amplify the ground motions but are not included in the crustal structure models used to compute the synthetic time-histories. Secondly, a new distance metric based on the computed theoretical decay curves is introduced which should have the ability to model the complex decay of strong ground motions. The ability of this new distance metric to reduce the associated scatter in empirically derived equations for the estimation of strong ground motions is tested. It is found that it does not lead to a reduction in the scatter but this is thought to be due to the use of crustal structure models that are not accurate or detailed enough for the regions studied. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
72.
Land surface evapotranspiration is an important component both in earth surface heat and water bal-ance, on whose budgets weather and climate depend, to a great extent, for their changes are responsible for the formation and variation of vegetation features on the globe. Besides, the evapotranspiration is an im-portant topic of short-term flood forecasting and the estimation of runoff from mountainous sides. As a result, the problem as to the evapotranspiration has been one of the concerns in …  相似文献   
73.
巫山县污水处理厂高填方地基湿化变形试验研究   总被引:3,自引:5,他引:3  
傅旭东  邱晓红  赵刚  邹勇  刘祖德 《岩土力学》2004,25(9):1385-1389
结合巫山县污水处理厂高填方工程,选取压实粘性土样,在室内进行了接近实际应力路径下的“单线法”湿化变形试验,研究了土样在不同的压实度、固结压力和湿化历史下的湿化机理、湿化前后的应力.应变关系及强度变化规律。取得的湿化变形试验成果表明,湿化使土样的变形模量和强度均有所降低;湿化变形不仅包括湿化体应变,而且包括湿化偏应变;随着压实度的增加,湿化变形减小。试验成果为巫山县污水处理厂高填方地基的填筑设计、控制湿化变形的措施和附加压密措施提供了依据。  相似文献   
74.
矿产品供需关系决定矿产品价格的市场走向,运用供需二维图解可以预测矿产品供需动态,给出精确的供需二维图要注意资源增加与减少、代用材料和新产品开发等因素,指出精心积累矿产品供需资料,仔细观察供需关系,可以预测矿产品价格和市场走向。  相似文献   
75.
云南会泽超大型铅锌矿床成因研究中的几个问题   总被引:6,自引:0,他引:6  
位于川-滇-黔铅锌多金属成矿域中南部云南会泽超大型铅锌矿床可能是一种新的铅锌矿床类型,该类铅锌矿床明显特征是规模大、品位富、伴生有用元素多,暗示其成矿环境较为特殊。从成矿时代、成矿物质来源、成矿流体来源与演化,以及峨眉山玄武岩与成矿的关系等方面分析了会泽超大型铅锌矿床的研究进展及国内外研究现状,认为矿床成矿时代与西南大面积峨眉山玄武岩成矿时代相近,成矿物质和成矿流体具有“多源性”,成矿流体存在均一化过程,区域大规模流体运移在该区铅锌成矿过程中具有重要意义,峨眉山玄武岩岩浆活动与铅锌成矿具有密切的成因联系,矿床可能为“均一化成矿流体贯入成矿”的产物。  相似文献   
76.
This paper presents an attenuation relationship of peak ground acceleration (PGA) derived from Turkish strong motion data for rock, soil and soft soil sites and an iso-acceleration map of Turkey based on this relationship. For the purpose, among all the three-component accessible records, 221 records from 122 earthquakes that occurred in Turkey between 1976 and November 2003 were selected. The database was compiled for earthquakes with moment magnitudes (Mw) and PGA values ranging between 4.1 and 7.5, and 20 and 806 gal, and distances to epicenter considered in the database were between 5 and 100 km. From the regression analysis of the data, an attenuation equation of PGA considering rock, soil and soft soil conditions was developed. The PGA values predicted from the equation suggested in this study and those both from a few domestic equations and some imported equations were compared. In addition, an iso-acceleration map of Turkey was constructed using the suggested attenuation equation and considering both known active faults and epicenter locations of the earthquakes that have occurred in Turkey.  相似文献   
77.
将传统上广泛使用的“种子法”和“矢量求交法”的思想相结合 ,提出了一种基于约束Delaunay三角网结构的多边形生成算法。详细描述了该方法的基本思想 ,在实验基础上分析了算法的特点。  相似文献   
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Introduction Estimation of an attenuation relationship for strong ground motion parameters has been an interesting research subject in the field of engineering seismology and has played a very important role in seismic safety evaluation, seismic zoning, seismic hazard evaluation of major constructions, etc. At present, the generally used parameters include peak acceleration, peak velocity and elastic response spectrum. Such parameters mentioned above are essentially independent of the duration…  相似文献   
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